---
title: "Can you explain how to customize API key authentication behavior in .NET Core?"  
description: "Can you explain how to customize API key authentication behavior in .NET Core?"  
author: "Rocky Dada"  
published: 2023-08-30  
updated: 2023-09-02  
canonical: https://www.mindstick.com/forum/159742/can-you-explain-how-to-customize-api-key-authentication-behavior-in-dot-net-core  
category: "web api"  
tags: ["c#", ".net", ".net core api"]  
reading_time: 3 minutes  

---

# Can you explain how to customize API key authentication behavior in .NET Core?

[Describe](https://www.mindstick.com/interview/12752/what-is-ddms-describe-some-of-its-capabilities) how to customize the [behavior](https://www.mindstick.com/forum/159354/runtimeexception-and-exception-behavior) of [API key authentication](https://www.mindstick.com/forum/159739/what-is-api-key-authentication-in-dot-net-core-web-api), such as enforcing specific [rules](https://www.mindstick.com/articles/43901/blackjack-rules) or adding additional checks during the authentication process.

## Replies

### Reply by Aryan Kumar

[API](https://www.mindstick.com/articles/12641/instagram-api-upgraded-to-facebook-graph) key [authentication](https://www.mindstick.com/blog/177/authentication-and-authorization-in-asp-dot-net) is a type of authentication that uses a secret key to authorize access to an API. The secret key is typically sent in the header of the HTTP request.

To customize API key authentication behavior in .NET Core, you can use the `ApiKeyMiddleware` class. The `ApiKeyMiddleware` class allows you to customize the following aspects of API key authentication:

- The header that the API key is sent in.
- The format of the API key.
- The way that the API key is validated.
- The way that unauthorized requests are handled.

To use the `ApiKeyMiddleware` class, you need to add it to the middleware pipeline in your application. You can do this by adding the following code to your `Startup` class:

C#

```plaintext
app.UseMiddleware<ApiKeyMiddleware>();
```

You can then customize the behavior of the `ApiKeyMiddleware` class by setting the appropriate properties. For example, to change the header that the API key is sent in, you can set the `HeaderName` property.

The following code shows how to change the header that the API key is sent in:

C#

```plaintext
app.UseMiddleware<ApiKeyMiddleware>(
    options => options.HeaderName = "X-Api-Key");
```

You can also customize the format of the API key by setting the `KeyFormat` property. The `KeyFormat` property can be set to one of the following values:

- `PlainText`: The API key is sent in plain text.
- `Hashed`: The API key is hashed before it is sent.
- `Encrypted`: The API key is encrypted before it is sent.

The following code shows how to change the format of the API key:

C#

```plaintext
app.UseMiddleware<ApiKeyMiddleware>(
    options => options.KeyFormat = ApiKeyFormat.Hashed);
```

Finally, you can customize the way that unauthorized requests are handled by setting the `OnUnauthorized` property. The `OnUnauthorized` property can be set to a delegate that will be called when an unauthorized request is received.

The following code shows how to change the way that unauthorized requests are handled:

C#

```plaintext
app.UseMiddleware<ApiKeyMiddleware>(
    options => options.OnUnauthorized =
        (context, exception) => context.Response.StatusCode = 401);
```

By customizing the behavior of the `ApiKeyMiddleware` class, you can tailor API key authentication to the specific needs of your application.

Here are some additional considerations when customizing API key authentication behavior in .NET Core:

- **The header that the API key is sent in:** The header that the API key is sent in should be a header that is not commonly used by other applications.
- **The format of the API key:** The format of the API key should be secure and difficult to guess.
- **The way that the API key is validated:** The API key should be validated against a secure store.
- **The way that unauthorized requests are handled:** Unauthorized requests should be handled in a way that does not compromise the security of the application.

By following these considerations, you can ensure that API key authentication is secure and effective.


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Original Source: https://www.mindstick.com/forum/159742/can-you-explain-how-to-customize-api-key-authentication-behavior-in-dot-net-core

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